You are using bad instrumentation. You don't have 100% RH.
To understand sweating, you have to understand relative humidity and dew point.
Dew point is a measurement of the actual moisture in the air. Dew point is not relative to the temperature.
Dew point is the temp moisture begins to condensate on a smooth surface.
You take the dew point and the temp to determine the relative humidity.
The temp of your door & places where the moisture is forming is under the dew point of the space.
So you have a 35degree dew point in your shop and your door is 20 degrees it is going to sweat.
The only 2 solutions are. 1. Heat up the door over the dew point OR. 2. Bring down the dew point in the space to below the temp of the door.
A common way to bring down dew point is to run an AC coil. The water condenses on the coil and runs out a drain & is therefore removed from the air. This is what keeps your house dry in the summer. When controlling humidity, it is common to cool the air down to the desired dew point and reheat it to be comftorable.
Your dew point is going to be to cold to do this. ^^^. (dew point cannot exceed the temp).
They make desiccant dehumidifeirs, but they are energy HOGs.
I know none of this info helps you fix your problem, but I hope this helps you understand what's going on anyway.
Total climate controlled garages are need for storing antique cars and keeping machinery and tools from developing surface rust. All five of my garages have central forced air heating and air-conditioners. Neither will keep the humidity down to a consistent 40%. Particularly in changing weather conditions. So I run a 65 pint dehumidifier in each garage year round. They have a humidistat that will shut them off once the humidity is below the set point... I have mine mounted on shelves near the furnace... To eliminate dumping the reservoir all the time, I have the condensate connected directly to a drain...
